Powerline Control Interface in CENELEC (EU) A-D Bands  Frequency and Amplitude Modulation Transmitter

ABSTRACT

An apparatus is disclosed where a Powerline interface is used to transmit data into the powerline grid network, where the powerline interface is pulling the required transmit energy from the power grid network, where the powerline interface is transmitting data using standard narrow band modulation such as ASK, FSK, S-FSK, where the transmitted data are passed on to the powerline interface by the use of an “Input signal” adapation stage, where an error calculation and a comparisson to a “Triangle” signal is performed to create a command signal used to enable the transmission of data by providing enough voltage to polarize the Transistor (i.e: MOS FET) used in the powerline path.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. pending patentapplication Ser. No. 13/227,891 entitled “Powerline Control Interfacefor Frequency and Amplitude Modulation Transmitter” which was filledSep. 8, 2011 in the US Patent & Trademark Office which claims thebenefits of priority to the filing date of U.S. provisional patentapplication No. 61/495,924 entitled “New innovative PowerlineCommunication (PLC) solutions” which was filed Jun. 10, 2011. Both areincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a type of Powerline Communicationinterface in the low frequency bands (from few KHz to few hundred KHz),also called BF power line coupler, and more specifically to an ultra lowpower, low cost Powerline Interface (PI) between a PHY standardmodulation, demodulation (MODEM) and the power wires used to connect alldevices in their eco-system (Alternating Current [AC] or Direct Current[DC] depending on the application).

BACKGROUND OF THE INVENTION

Evolution of existing Powerline Communication technologies imposes aneed to improve performances of the power line coupler, morespecifically when it comes to the use of PLC communication solution inthe low frequency bands (denoted LFB) going from a few KHz to fewhundreds of Khz.

While a continuation of the U.S. pending patent application Ser. No.13/227,891 entitled “Powerline Control Interface for Frequency andAmplitude Modulation Transmitter”, the focus of our invention remains atthe Physical Layer in PowerLine Communications (PLC) environment.

Consequently the present invention was conceived to improve theperformances of a Powerline Interface (PI), in the LFB plan, to transmitdata on the power line by using (“pulling”) the required current(denoted: Current) from the power line and therefore reducing theoverall power consumption of the transmit system to only few milli-wattsrequired by the electronics of the PI.

As a consequence of this present invention, power dissipation issues inthe LFB for some of the components directly connected to the power lineare significantly reduced and therefore facilitating the deployment ofstandard modulation PLC solutions into forms factors that were notpossible until now due to some reliability concerns.

Furthermore, the goal of the present invention is to provide a solutionfor the PLC Line coupler, which is independent of the type of PHY narrowband modulation (ASK, FSK, S-FSK, etc . . . ) and the frequency bandplan. With proper adaptation of some of the electronics, the inventioncan be used in any of the LFB relevant to the smart grid market, suchas:

-   -   CENELEC (EU) A/B/C/D bands (3 Khz to 148.5 KHz),    -   ARIB (Japan) band (10 Khz to 450 Khz),    -   FCC (US) bands (10 KHz to 490 KHz)

OBJECT OF THE INVENTION

The reason for the invention is to improve performances in the lowfrequency band (LFB) compared to PLC coupler as defined in the U.S.pending patent application Ser. No. 13/227,891 entitled “PowerlineControl Interface for Frequency and Amplitude Modulation Transmitter”.While still looking at providing an ultra low power, low cost and smallform factor Powerline Interface (PI) as part of a PLC Communicationsystem, the object of this invention focus on: a) performancesimprovement in the LFB; b) power dissipation improvement over previoussolution and mostly in the LFB. Like most of the traditional PLCcommunication system, the invention is used in an AC power environment,but can be used also in a DC power distribution network, thus dependingon the applications.

An additional object of the present invention provides improvements interm of system power consumption by generating a Transmit signal(“Pulling”), in the LFB Plan, from the power line versus existing PLCtechnology that drive transmit power (“Pushing”) into the power linesusing inductive or capacitive coupling to the power wires.

Further object of the present invention is to use a “V_Enable” signal toenable the transmission of data by providing enough voltage to create areference signal used in the Input signal path. Therefore, the rhythm ofthe apparition of the modulation signal is controlled. Additionally, thevoltage, when set to zero volt, disables all the transmit path of thesystem and therefore turn off the overall supply power needed for thetransmit path.

Another object of the invention is to be able to use any existing narrowband modulation as part of the overall PHY modulation stage of thesystem. Standard modulations such as ASK, FSK, S-FSK, etc . . . within adefined frequency bandwidth can be transmitted through the use of theinvention.

Further object of the invention is to leverage existing Receiverprocessing circuit (DSP) to receive data signals, which are compatiblewith the existing systems when using the same modulation and frequencybands. Therefore, the invention allows for some compatibility withsystems already deployed in the field.

Further object of the invention provides a more desirable low cost,small form factor solution to provide a PLC line coupler due to thereduced number of components needed.

In addition to the above, the invention is also independent of theprotocols used by the upper layers and can find its use in markets like,Smart meters, Home Energy Management network, Plug-In Electric Vehicles(PEV), Photovoltaic (PV) solar power markets, to name only few of them.

One can also use this invention in any DC environment like PVoptimizers, Home Automation (i.e: HVAC control system), AC/DC or DC/DCPower supply markets (i.e: it can be used in the context of “smart”power supply allowing a Grid operator to have a direct impact on the useor not of equipment in its network).

SUMMARY OF THE INVENTION

Embodiments of the present invention is to create a method to generateStandard Transmit signal (“Pulling”) from the power line as it connectsbetween two wires of the power network through a diode rectifier (toinsure proper signal adaptation) followed by a Transistor (i.e: MOS FET)and some adapted Filtering circuit to significantly reduce the requiredpower for the transmit stage for modulating the signal of a networkvoltage.

Further embodiment of the present invention is to have a single powerrail on the board as the transmit stage is pulling power from the powerline through the use of a Transistor (i.e: MOS FET) and an adaptedFiltering circuit and therefore eliminating the need for other Transmitpower supply rail (i.e: no need for a 12 Voltage rail).

Further embodiment is to generate a Command signal for the Transistor(i.e: MOS FET) that will create the Standard Transmit signal from thepower line. The Command signal is generated during the transmission bycomparing a pre-defined Triangle signal and a Generated Error signal.Some electronics are used to produce both the Triangle and the errorsignal voltages allowing a Linear Amplifier to commute and then commandthe Transistor (i.e: MOS FET) by creating the minimum power consumptionfor polarization of Transistor (i.e: MOS FET).

Another embodiment of the present invention is to use a Linear Amplifiercircuit to subtract a Scaled Standard Modulation signal to a ReferenceTransmit signal and therefore creating an Error signal that will use tocommand the Transistor

(i.e: MOS FET) and in order to generate Standard Transmit signal(“Pulling”) from the power line.

Additional embodiment of the present invention is to use aCapacitor/Resistors circuit to offset and scale the Input signal to beused to: a) generate a Command signal for the Transistor (i.e: MOS FET);b) to define the transmit power level of the Standard Transmit signal(“Pulling”) from the power line.

Further embodiment during the idle phase (reception), is to set theV_Enable signal to zero volt, reducing the overall supply power of thetransmit path.

It is desirable that the amplitude of the alternative voltage (AC) ofthe Power distribution network is greater than the threshold of theTransistor (i.e: MOS FET) to be polarized. This Current modulation isindependent of the network impedance as long as it stays higher than therequired voltage for the polarization of the Transistor (i.e: MOS FET)and inductance/resistor voltage.

Embodiment of the present invention is to be able to generate somemodulation signals leveraging Standard Modulation (such as ASK, FSK,S-FSK, etc . . . ) as they are used in many smart grid system and thosebeing in the LFB, such as CENELEC bands. Higher frequency bands can alsosupported with the present invention, but will be better supported bythe US pending patent application No 13227891 entitled “PowerlineControl Interface for Frequency and Amplitude Modulation Transmitter”.

Further embodiment of the invention includes a processing circuit toreceive data signals, which are compatible with system using sameStandard Modulation (same modulation and frequency bands) than thepresent invention. Therefore, the invention allows to keeping somecompatibility (interoperability) with systems already deployed in thefield.

An additional embodiment of the present invention is the possibility touse the invention in a DC power distribution environment by usingsimilar electronics concept to the AC system but without the frontadaptation stage created by the diode rectifier circuit.

Furthermore, the present invention in the context of a DC powerdistribution environment supports the transmission of the signal in acontinuous mode.

Embodiments of the present invention are directed to better control ofthe amplitude of the modulated signal, in particular with regard toelectromagnetic compatibility rules of ElectromagneticInterference/Electromagnetic Compatibility (EMI/EMC).

BRIEFS DESCRIPTIONS OF THE DRAWINGS

The present invention will be better understood and fully appreciatedwhen read in conjunction with the appended drawings. It should beunderstood, however, that the present invention is not limited to theprecise arrangements and instrumentations as shown in the drawings.

FIG. 1 shows a conventional Powerline Communication coupler.

FIG. 2 presents a modified line coupler reflecting the embodiments bringby the present invention.

FIG. 3 shows an electrical circuit diagram of the line coupler 13reflecting the embodiments bring by the invention when use in an ACpower distribution environment.

FIG. 4 shows signals of the transmission chain.

FIG. 5 shows signals of the Transistor Q1 42 to generate the Transmitsignal on the powerline.

FIG. 6 shows signals of the generated Transmit signal on the powerline.

DETAILED DESCRIPTIONS OF THE EMBODIMENTS

FIG. 1 shows a complete system 1 leveraging existing PLC technology forLFB (or High) frequency band plan. Unfortunately, most of thecommunication system used today in most of the PLC solution is a“Pushing” communication system 1 compare to our invention approach,which is a “Pulling” communication system 8. As a result by leveragingthe present invention, systems, like smartgrid systems, are a) most costeffective solution due to its reduced number of components; b) ultra lowpower energy inefficient communication solution due to the absence ofpowerline drivers in the communication interface; c) improving theperformances of the overall system due to need of less power supply forthe overall system. Other advantages of this type of solution aresecurity, remote management, etc . . .

In this system 1, Data 4 and Modulation 5 blocks are related to thePhysical layer (PHY) and allow to generating Standard Modulation signalsfor the line coupler 7. Those signals are then pass on to a line driver6 to create the transmit power signal to go through the line coupler(i.e: U.S. Pat. No. 7,078,982). Traditional line couplers are most ofthe time either inductive (using transformers) or capacitive (usingcapacitors). As mentioned in the FIG. 1, power supply 3 for these typesof couplers can be up to few watts in the context of narrow frequencyband system and even higher when using large frequency band system.

U.S. Pat. No. 7,078,982 provides a method wherein such high frequencyoscillations are used to carry data through an electric network. Thehigh-frequency oscillations are generated by the line coupler,comprising an electric element in series with a switch, the whole beingconnected between two wires of the electric network. A control signalcarrying data is applied to the switch and alternately allows the switchto be closed and opened. Thus, the rhythm of the apparition of thehigh-frequency oscillations is controlled.

FIG. 2 shows a system 8 leveraging the present invention 13 which alsosupport either narrow or large frequency band in any frequency band planfor transmission of Standard Modulation. In this new system 8, Data 11and Modulation 12 blocks are related to the Physical layer (PHY) and aresimilar to the blocks shown in FIG. 1.

The modulation signals for the line coupler are then going through someelectronics (represented in this FIG. 2 as a Linear Amplifier 14) usesto off-set, scale and control the output impedance, which is creating aCurrent modulation to be applied to Transistor (i.e: MOS FET 15) whichis pulling the transmit power from the power lines contrarily to theline coupler 7 in FIG. 1.

As a result (as shown in FIG. 2), power supply 10 requirement for thisnew system is only a few ten of milli-watts for both a narrow frequencyband system and a large frequency band system.

The U.S. pending patent application Ser. No. 13/227,891 entitled“Powerline Control Interface for Frequency and Amplitude ModulationTransmitter” allows improvements in term of types of modulation totransmit over power wires versus existing PLC technology leveragingsimilar “Pulling” type of coupling to the power line.

The present invention allows performances improvements in term ofStandard Transmit signal related to the power line impedance. It alsoallows further improvement in term of reducing the power dissipation ofthe overall system and more importantly of the Transistor 15 connecteddirectly to the powerline.

Existing PLC technology generates transmit signal for “amplitudemodulation” only by creating a single transmit Pulse (WO 2006/008381International Application number) or by creating Multiple transmitPulses (FR 08 01520 and U.S. Ser. No. 12/185,312) for a single data bitversus the present invention which can support any Standard narrow bandModulations (such as ASK, FSK, S-FSK, etc . . . ) with limited frequencybandwidth depending on the chosen standard modulation (StandardModulations).

FIG. 3 shows a system representing the invention in the context of an ACpower network. The description of the present invention is mostlyrelated to the transmission part of a PLC system and is comprising ofthree (6) blocks for transmitting data through the line coupler:

-   -   The Off-set & Scale Input signal block 16    -   The Error calculation block 17    -   The Command block 18    -   The Transmit signal block 19    -   A Low Pass Filter block 20    -   The Rectifier, 21.

The Transmit signal block 19 is mostly acting like a “Buck” convertor tofacilitate the transmission of the Standard Modulation signal (Signal)by creating enough voltage to be pulled from the powerline. Modulationstype such as ASK, FSK, S-FSK, etc . . . can be used with the invention.

The following considerations are critical to the invention:

-   -   A regulated generator of current is used and directly connected        to the power supply 22 (V+). It is important to notice that 22        (V+) voltage can be at +5V depending of the minimum voltage        required to polarizing Transistors    -   (i.e: MOS FET) 42 (Q1).    -   During the idle phase (reception), the 22 (V_Enable) signal is        set to zero volt to disable all the transmit path of the system        and therefore reducing the overall supply power needed for the        transmit path.    -   The V_Enable, 22, connection is used as transmission enable        signal and can be also [V+] and is used as a power supply for        the PLC Line coupler transmit side. During the transmission        phase, 22, V_Enable signal is active.    -   When 22 (V_Enable) is active, the Input signal 23 is transmitted        through the electronics of the block 16. The purpose of this        block is to generate a Reference signal with no offset and        amplitude that translate directly into the level of the power        Standard Transmit signal on the powerline. The offset is done by        the capacitor 24 and the scale function by a resistive divider        25 and 27 (resistors).    -   The Reference signal from block 16 is then subtracted from the        VRef Out signal 28 coming from the Transmit block 19. Vref_out        signal 28 corresponds to an image of the current absorbed from        the grid. The variation of this current is equivalent to the        desired impedance modulation. So using the desired reference        signal and created Vref_out, one can build an Error signal 33        that will be used for regulation by the Command block 18.    -   The Command block 18 must first perform a comparison with the        generated Error signal 33 and a created Triangle signal 34. The        result of this comparison done by 35 (Amp Linear) create the        Command signal 37 for which the ON and OFF cycle is directly        dependent of the Error signal 33. When ON, the minimum power        consumption for polarization of the Transistor (i.e: MOS FET) 42        (Q1) is applied. No power is transmitted on the line from the        power supply. Only the coulombs to trigger the Transistor (i.e:        MOS FET) 42 (Q1) are needed.    -   Block 34 is Triangle generator use to perform the comparison and        its electronics is public knowledge and not relevant to this        invention.    -   Modulation thru the transmit block 19 and more specifically        Transistor (i.e: MOS FET) 42 (Q1) is achieved by sending the        data to modulate thru the “Input” signal 23 to create the        voltage for the command of Transistor (i.e: MOS FET) 42 (Q1).    -   Block 19 is designed in a similar way than a voltage convertor        used in a Buck mode (step-down mode). The duty cycle of the Buck        is dependant on the Command signal 37. As a result the Inductor        40 is accumulating energy when the command signal 37 is ON. When        OFF, then the energy is transferred to 40 (inductor) and 38        (Resistor). 39 and 40 are making a low pass filter with a cutoff        frequency that have be higher than the frequency band used by        the Standard Transmit signal. 38 and 39 are also a low pass        filter with a cutoff frequency that should also be higher than        the frequency band used by the Standard Transmit signal. Voltage        at 39 is unstable as it is also transferring energy in 38.    -   As a result, Transistor 42 periodically “pulled” energy from the        powerline in direct relation with the Error signal 33 as a        result of its adaptation to the Input signal 23. The        communication power is not provided by the transmitter as in        traditional PLC solution but it is pulled from the use of the        Transistor (i.e: MOS FET) 42 (Q1), and other circuit (38, 39,        40) and therefore allowing to reduce significantly the required        power for the transmit stage and also reducing the complexity of        power supply on the board (i.e: not need for a 12 Voltage rail).    -   The Low Pass Filter block 20 is made of an inductor 45 and a        capacitor 44 with a cut-off frequency higher than the frequency        used by the Standard Modulation, but lower than the 2^(nd)        harmonic created by the PLC Line coupler. As a result only the        LFB used by the Input signal will be found on the powerline.    -   The bridge rectifier (Rectifier 21), which is directly connected        to the Phase and

Neutral wires of the power line, is here to insure proper signaladaptation of the AC signal from the powerline. This allows theTransistor (i.e: MOS FET) 42 (Q1) to pull all required current duringboth the positive and negative phases.

-   -   The 30 (Amp Linear) present a feedback loop connected to VRef        Out 28, so the voltage at 39 (R1) is equal to the voltage “Vref”        42 at any time. The Current drained from the grid presents the        same modulation than the desired Signal.    -   This Current modulation (“I Q1_R1”) 35 is independent of the        network impedance as long as it stays higher than the required        voltage for the polarization of Transistor (i.e: MOS FET) 47        (Q1) and as long as grid impedance is higher than 39 (R1).    -   When a DC Environment, mostly what is needed is to remove the        bridge rectifier (Rectifier 21) to insure proper signal        adaptation. It is important to notice that 22 (V+) voltage does        not have to be a similar voltage to the DC line voltage and can        be the same as for an AC system. Therefore it can be at +5V        depending of the minimum voltage to polarizing Transistors (i.e:        MOS FET) 42 (Q1).

FIGS. 4 and 5 show experimental signals of the transmission chainleveraging the present invention. The situation is an AC grid presentinga 50 Hz frequency and 220 Volt peak-to-peak magnitude. The Input signal23 is a pure tone at 100 KHz and 2 Volt peak-to-peak magnitude, which isused in Europe for some FSK modulation in a smartgrid environment.

FIG. 4 shows how the original signal 23 (“Input signal”) is scale togive a reference signal 46, after being scale down through theelectronic block 16. Signal 47 is the VRef_Out signal and is subtractedfrom signal 46 to create the Error signal 48 used as an input by thecommand block 18. Signal 49 is a Triangle signal of 2.2 MHz generated bythe Triangle electronics 34 and used also as an input by the commandblock 18. Command signal 50 is the result of comparing 48 and 49 andwill be used to command the Transistor Q1 42. 51 show the PSD of theCommand signal and 52 show the one of the Error signal.

FIG. 5 is showing how the Command signal is used to drive the couplerand creates an Output signal 56. Signal 53 show the V_(DS) on theTransistor Q1 42 as the result of applying the Command signal 50 while54 show the current. 55 and 56 show the voltage respectively at theinductor 40 and 45. 57 show the voltage VRef_out signal 28.

FIG. 6 shows the grid voltage modulation (“Phase” signal) 58 for acomplete period of the Input signal (10 μs). The 59 follows the Inputsignal modulation 23 except when the grid voltage is very low, lowervalue than the Transistor (i.e: MOS FET) 47 V_(DS) (Q1) polarizationvalue (at zero crossing time). At that moment no signal is modulated.

60 show the PSD for the VRef_out signal 57 with the various harmonicswhile 58 is the PSD of the Phase signal and show the impact of the Lowpass Filter block 20 as no harmonics above 100 KHz are on the phaseline.

1. A method to leverage power in an electrical network wherein acontinuous modulated signal for communication purposes is transmitted bycreating a impedance modulation.
 2. The method of claim 1 wherein saidimpedance modulation has a coupler comprising of: a Transistor connectedto said electrical network; an impedance in series connected to saidTransistor wherein said impedance in series allows feed back informationfor said Transistor V_(GS) regulation; an electronic circuit includinglinear amplifiers used to control said Transistor current.
 3. The methodof claim 2 wherein said coupler further comprises components forelectronic protection.
 4. The method of claim 2 wherein said Transistoris connected to said electronic network through impedance.
 5. The methodof claim 2 wherein said linear amplifier controls said Transistorcurrent.
 6. The method of claim 2 wherein a minimum voltage sufficientfor power consumption for polarization of the Transistor is appliedthrough said linear amplifier.
 7. The method of claim 6 wherein duringidle phase a voltage of zero volt is applied through said linearamplifier.
 8. The method of claim 2 wherein said electrical networkfurther comprises an adaptation circuit for monitoring voltage carriedby said network.
 9. The method of claim 8 wherein said adaptationcircuit further supplies a command signal.
 10. The method of claim 1wherein said modulated signal is Standard modulation.
 11. The method ofclaim 1 wherein said network further comprises a processing circuit toreceive signals.
 12. The method according to claim 2 wherein saidcoupler can be integrated into System on Chip.
 13. The method accordingto claim 1 where is said electrical network is Alternate Current. 14.The method according to claim 1 where is said electrical network isDirect Current.
 15. The method according to claim 1 where is applicableto an electronic system managing DC/AC conversion.
 16. The methodaccording to claim 1 where is applicable to an electronic systemmanaging DC/DC conversion.
 17. The method according to claim 1 where isapplicable to an electronic system managing AC/DC conversion.
 18. Aapparatus for impedance modulation transmitting continuous modulatedsignal for communication purposes in an electrical network comprisingof: a Transistor connected to said electrical network; an impedance inseries connected to said Transistor wherein said impedance in seriesallows feed back information for said Transistor V_(GS) regulation; alinear amplifier used to control said Transistor current.
 19. Theapparatus of claim 18 wherein said Transistor is connected to saidelectronic network through impedance.
 20. The apparatus of claim 18wherein said linear amplifier controls said Transistor current through aTransistor driver.
 21. The apparatus of claim 18 wherein a minimumvoltage sufficient for power consumption for polarization of Transistoris applied through said linear amplifier.
 22. The apparatus of claim 18wherein during an idle phase a voltage of zero volt is applied throughsaid linear amplifier.
 23. The apparatus of claim 18 wherein saidnetwork further comprises an adaptation circuit for monitoring voltagecarried by said network.
 24. The apparatus of claim 23 wherein saidadaptation circuit further supplies a command signal.
 25. The apparatusof claim 18 wherein said modulated signal is Standard modulation. 26.The apparatus of claim 18 wherein said network further comprises aprocessing circuit to receive signals.
 27. The apparatus of claim 18wherein said coupler can be integrated into System on Chip.
 28. Theapparatus of claim 18 where is applicable to an electronic systemmanaging DC/AC conversion.
 29. The method according to claim 1 where isapplicable to an electronic system managing DC/DC conversion.
 30. Themethod according to claim 1 where is applicable to an electronic systemmanaging AC/DC conversion.